Category
8 articles · Referenced to BS 7671 · Free
The consumer unit — often called the fuse box — is the control centre for all the electrical circuits in your home. It contains the main switch, the MCBs (circuit breakers) for each circuit, and RCD protection. Since 2016, consumer units in the UK must be made of metal. If yours is old or plastic, an upgrade is strongly recommended.
Whether you need to upgrade your consumer unit
How much a new consumer unit costs in 2026
Why MCBs trip and how to identify the fault
The difference between MCBs, RCBOs, and RCDs
Metal vs plastic consumer units and the regulations
Adding new circuits to your consumer unit
Safety note: Never work inside a consumer unit yourself. Even with the main switch off, the meter tails remain live. Only qualified electricians should work on consumer units.
Circuit Protection Devices
1 question
What is the difference between an MCB and an RCBO?
An MCB protects against overload and short circuit. An RCBO does both of those AND protects against electric shock by detecting earth leakage — it's a two-in-one device.
Read answer →Consumer Unit Design
1 question
How many circuits should my consumer unit have?
A typical 3-bedroom house needs at least 8–12 circuits. Modern homes with EVs, solar, and smart home technology may need 14–18 or more.
Read answer →Consumer Unit Types
1 question
What is a split-load consumer unit?
A split-load consumer unit divides circuits into two groups — one group is RCD-protected, the other is not. It's an older design that's been largely replaced by full RCBO boards.
Read answer →Fault Finding
1 question
Why does my MCB keep tripping?
An MCB trips due to overload or a short circuit. Unplug appliances on that circuit, reset it, and plug them back one at a time to find the cause.
Read answer →Upgrades
2 questions
When does my consumer unit need upgrading?
Your consumer unit needs upgrading if it's more than 25–30 years old, has no RCD protection, uses old rewirable fuses, or has failed an EICR inspection.
Read answer →Do I need to upgrade my fuse box?
If you have old rewireable fuses, no RCD protection, or a plastic consumer unit fitted before 2016, upgrading is strongly recommended.
Read answer →